What Is a Basketball Stats Calculator and How Does It Work?
A basketball stats calculator converts a box score — points, field goals, 3-pointers, free throws, rebounds, assists, steals, blocks, and turnovers — into the shooting percentages and efficiency ratings coaches and analysts use to evaluate a player's performance. It answers questions raw counting stats cannot, like how efficiently a player scored relative to how many shots it took.
Effective field goal percentage (eFG%), popularized in Dean Oliver's 2004 book Basketball on Paper, is calculated as eFG% = (FGM + 0.5 × 3PM) ÷ FGA × 100, where FGM is field goals made, 3PM is 3-pointers made, and FGA is field goals attempted. The 0.5 weighting exists because a made 3-pointer is worth 50% more than a made 2-pointer, so raw FG% understates the value of accurate 3-point shooting.
True shooting percentage (TS%) goes further by folding in free throws: TS% = PTS ÷ (2 × (FGA + 0.44 × FTA)) × 100, where PTS is total points, FTA is free throws attempted, and 0.44 is Dean Oliver's coefficient estimating the share of free-throw trips that consume a full possession. According to publicly tracked NBA season averages, the league-wide TS% typically sits between 56% and 58%, with elite scorers regularly posting 60%+.
How to Use This Basketball Stats Calculator
Enter a single game's box score, or totals across multiple games, and every stat updates instantly. Here is what each field means:
- PTS, FGM/FGA, 3PM/3PA, FTM/FTA: The core shooting line. FGA should include all field goal attempts (2-point and 3-point combined); 3PA is the subset that were 3-point attempts.
- REB, AST, STL, BLK, TOV: Rebounds, assists, steals, blocks, and turnovers — the non-shooting counting stats used in the efficiency score and assist-to-turnover ratio.
- Games Played (GP): Leave at 1 for a single game. Enter the number of games if the totals above are a season or stretch of games — this unlocks per-game averages (PPG, RPG, APG).
The same formulas apply whether the box score comes from the NBA, WNBA, EuroLeague, FIBA international play, NCAA, or a recreational league — eFG%, TS%, and the assist-to-turnover ratio are unit-less ratios that do not depend on league, court size, or country.
What Do FG%, eFG%, and TS% Mean?
Each shooting metric answers a slightly different question, and the gap between them tells its own story: a player with a low FG% but a much higher eFG% is a 3-point specialist, while a big gap between eFG% and TS% usually points to heavy free-throw production.
| Stat | Elite | Average | Below Average |
|---|---|---|---|
| FG% | 50%+ | 40% – 50% | Below 40% |
| eFG% | 55%+ | 45% – 55% | Below 45% |
| TS% | 58%+ | 50% – 58% | Below 50% |
| FT% | 85%+ | 70% – 85% | Below 70% |
The NBA's official Player Efficiency Rating (PER), created by analyst John Hollinger, normalizes per-minute production against league pace and requires season-long, league-wide data that a single box score cannot supply. This calculator instead reports a simplified box-score Efficiency Score — EFF = (PTS + REB + AST + STL + BLK) − ((FGA − FGM) + (FTA − FTM) + TOV) — the same style of formula the NBA itself has historically used for its efficiency leaderboards, which rewards positive production and subtracts missed shots and turnovers.
Frequently Asked Questions
What is a good field goal percentage in basketball?
A field goal percentage above 50% is considered elite and is typically posted only by efficient big men or high-percentage finishers; 40–50% is a normal range for most rotation players, and guards who shoot a high volume of 3-pointers often sit in the low-to-mid 40s while still being highly effective once eFG% accounts for made 3s.
How do you calculate effective field goal percentage (eFG%)?
eFG% = (FGM + 0.5 × 3PM) ÷ FGA × 100. The 0.5 multiplier credits each made 3-pointer as being worth half a field goal more than a 2-pointer, since it is worth 50% more on the scoreboard. An eFG% of 55% or higher is considered elite; the wider NBA average sits around 52–54%.
How is Player Efficiency Rating (PER) calculated?
Official PER, developed by analyst John Hollinger, starts from a box-score formula similar to the EFF score above but then adjusts every player's number for their team's pace and the league's scoring environment that season, and rescales the league average to exactly 15.00. Because that adjustment requires full-season, league-wide data rather than a single box score, this calculator reports the simpler, unadjusted box-score efficiency score (EFF) instead and states that difference explicitly.
What is a good assist-to-turnover ratio?
An assist-to-turnover ratio of 2:1 or higher is generally considered good and is common among starting point guards; a ratio below 1:1 means a player is turning the ball over more often than they are setting up a teammate's basket, which is usually a red flag for a primary ball-handler.